Wedding pros—from planners to photographers to DJs and more—watch dozens of couples tie the knot each year. And between fee negotiations, cake tastings and photos of the bridal up-do, they often quietly form an opinion about a couple's chances of success. Melanie King, a California-based event planner with ten years experience, admits that sometimes the writing's on the wall. "There are certainly warning signs," she says. "You see things and think, well, my Christmas card's going to get returned in two years"—a returned card with no forwarding address typically tells her that things have gone south for the pair. Here, King and four other wedding experts, some who choose to keep their identities under wraps, clue us in on the red flags.

1. The engagement ring isn't quite what it seems. Princess-cut diamond, or relationship time bomb? Sometimes it can go either way, says a jeweler in Crystal Lake, IL. In her 30 years in the business, she's witnessed a wide array of ring-related bad behavior. There was the guy that reused his ex-fiancée's ring, and another who tried to pass cubic zirconia off as the real deal. One woman refused to settle for the rock she was given, so she upgraded without her guy knowing. "Clearly there are issues with honesty here, as well as difficulty in managing expectations," says the jeweler. "But the guy who re-gifted? That's just plain cheap."

2. The groom is still talking about last night's strippers the morning of the wedding. "Going crazy at the bachelor party can be expected," says New York City photographer Dennis Kwan, who has shot some 100 weddings. "But it's another thing to go all out the night before your wedding. That's just not a good sign." Kwan remembers a particularly rowdy groom and his hungover groomsmen that couldn't stop talking about the previous night's "entertainment." When a man is about to make the biggest commitment of his life, his focus should be on the bride and not on his buddies and their testosterone-fueled hijinks.

3. In photos, the bride tries to have a supermodel moment rather than capture the day. Kwan says, "If a bride's goal is to look like she stepped out of the pages of a fashion magazine—lots of fierce non-smiling poses and dramatic shadows—there's something a little off about her priorities." While Kwan knows the type, he works only with brides who want to capture the pure joy of the day. "These are the kinds of memories you can look back on in later years and remember why you got married to begin with."

4. The bride and groom each secretly warn the planner about the other. King knows what it's like to be caught between a conniving pair. "About once a year I'll get a bride who will email me to let me know that her fiancé is cheap and she could use some help convincing him to spend money," she says. "Then the phone rings and it's the groom with his own agenda." King says charades like these make her nervous for what's to come. "Planning a wedding is a microcosm of your marriage," she says. "These issues are going to resonate throughout the entire relationship."

5. One partner is easily embarrassed by the antics of the other. For one New York City-based bandleader with over 15 years of experience, the occasional know-it-all client is standard stuff. But he senses trouble when one partner is quick to feel humiliated. "He's controlling and obnoxious and she's sitting there with a frozen smile on her face, wishing she could hide," the bandleader says. "If this is their normal operating procedure—with everyone from waiters to repairmen—I wonder how they'll make it."

6. The first look is totally lackluster. The first time a bride and groom lay eyes on each other in all their wedding-day glory should be unforgettable. It may also say something about the longevity of the marriage, according to San Francisco photographer John Griffin, who has worked in the industry for over 12 years. "In my experience, that moment tells all," he says. "The more emotional the couple is, the more likely they'll make it." Certainly, though, they don't have to melt into puddles of emotion (though that does make for captivating photos). An ear-to-ear smile, wide eyes and a hand clasped over mouth are also nice ways to acknowledge the big day.

7. The band is waiting to play and the couple still can't decide on their first dance. When a couple debates something for far too long, King senses that something's up. "The inability to make a decision is often a sign of apprehension," she says. "There's some discomfort somewhere." King had a couple who could not settle on a first dance song. They finally picked one at the reception, with the band waiting, but not before the bride had started to cry. "If they decide on a first dance without tears, it doesn't bode well for their future," says King.

8. The couple's choices are completely out of sync. King recalls a bride who had her eye on a bohemian hacienda for the ceremony, while the groom hoped for something more traditional. The biggest problem? She'd already signed the contract. "We called them 'the couple that shouldn't get married,'" King says. Though they each had an opinion, they were never on the same page. Are you banging your head against the wall? If it's a big struggle, it may not be the best fit."

9. The bride and groom don't spend any time together at the reception. The day of your wedded bliss should not be the day to take a breather, but the bandleader says on rare occasion he's seen it. The bride dances with her friends, while the groom drinks at the bar. Or, one mingles while the other sulks. Whatever the case, it's not a good omen. "These are the good times!" he says. "If the couple can't stick together during a celebration, how are they going to stay united through the truly tough times?"

10. Either the bride or groom gets too drunk. There's no real need for newlyweds to binge. Getting sloshed—like one of King's brides who openly announced that she and the groom had already consummated the marriage—is the quickest way to embarrass your new spouse. It's also a pretty blatant way to show your disregard for the family and friends who have worked so hard to make your celebration happen.

11. The bride or groom tries to live-tweet the event. If the groom must first put down his iPhone before he "may kiss the bride," or she holds up the processional so she can post one last single-girl selfie, you may have another case of off-kilter priorities. That's why Griffin often makes his couples hand their phones over to the maid of honor or best man until after the reception. Of course, nowadays you can hire someone to cover your party's social media, but that's a whole other story.